1. Field of the Invention
This invention relates to an apparatus for automatically mounting a valve bag to a filling spout of a filling machine.
2. Prior Art
Nowadays, the filling of valve bags with finely grained materials, such as cement, agricultural chemicals, etc. is almost always done with the aid of filling machinery. The machinery generally has several filling spouts to which valve bags are mounted which material is delivered to the bags. See for example: U.S. Pat. No. 3,215,173 to Rutherford describes a rotating bag filling and weighing machine wherein the bags are manually placed on the filling machine; U.S. Pat. No. 3,261,379 to Stockel et al describes a filling machine, wherein the material is fluidized, for packaging dry divided solid material. The apparatus may have a plurality of spaced apart filling spouts; U.S. Pat. No. 3,913,637 to Seals (the inventor of the invention described and claimed herein) describes a rotary bagging or filling machine; U.S. Pat. No. 4,019,546 to Hastrub describes a rotary type filling machine having a means attached thereto for automatically placing the valve bags on the spouts. The apparatus used for mounting the bag on the spouts is particularly designed for the rotary packer described therein.
There are thus, generally, two types of filling machines those that are rotary and those that are stationary in-line filling machines. Hastrup and Seals exemplify the rotary type filling machines. They generally comprise a number of filling spouts from which the bags are suspended by the valves. The spouts are usually uniformly distributed about the circumference of a circle and rotated about a vertical axis. Generally, bags are placed manually on the filling spout by an operator whose only task is to pick up the bags from a bag storage means and to place each one on an empty filling spout as it passes him. All other operations of the filling machine, including filling to a predetermined weight and removal of the bag may be automatic.
The stationary in-line fillers, as exemplified by Stockel et al, generally have a plurality of equally spaced apart filling spouts. The operation is very similar to the rotary filling machines, except that the operation requires the movement of the operator vis-a-vis the rotating of the machine.
The bags which are usually employed with such machines are generally called valve bags. These bags are almost always made of paper of different strength, but could in principle be made for example of plastic, e.g. polyethylene.
A valve bag has a front, sides and a back wall, as well as a bottom and a top. When the bag is stored, the bottom and top portions of the bag are folded over and juxtaposed against the front or back wall. As used herein these are called the top and bottom folds. The top of the valve bag is similar to its bottom, i.e. it is substantially closed on all sides, but in the end portion of the top, near one of the edges of the bag, there is provided a filling aperture which is also called a "valve" or "valve means", from which this type of bag derives its name. In the vicinity of the valve means, the top of the bag is provided with a tab which gives it a double wall configuration through which the filling spout is inserted. When the bag is being filled, the material poured into the bag rises toward the top and eventually pushes the tab located underneath the main top surface upwardly, so that when the bag is removed from the filling spout, it is in a substantially closed, filled up condition.
Even at the present time, most valve bags are mounted on the filling spouts of filling machines by hand. It is obvious that the above described process requires substantial manual labor and is correspondingly expensive. In principle, the repetitive nature of the process of mounting such bag suggests mechanization but apparently the properties of valve bags, whose shapes are not stable, and the properties of filling materials have been such that this process has had to be performed primarily by hand. Additionally, the valve bag must be taken from its storage means and then manipulated in a certain manner prior to being mounted on a filling spout. This manipulation includes, firstly, bending the top of the bag up from its normally parallel storage position in which it is juxtaposed against the front or back wall of the bag, and, subsequently opening the valve by lifting or spreading apart the two top regions of the bag which form the valve.
Additionally, the filling machines used nowadays, both the rotary and stationary in-line machines, generally have such short cycling times, i.e. primarily filling times, that they cannot be fully utilized and exploited by servicing the spouts by hand. This condition is particularly true when a single operator is required to service several filling spouts, which is usually the case. The result is poor exploitation of the capabilities of the filling machine and the irregular delivery of filling bags.
There have been several devices designed to perform the task of automatically mounting valve bags to filling spouts of filling machines. The aforementioned Hastrup attempts to accomplish this, however, Hastrup's apparatus can only be used with a particular type machine. U.S. Pat. No. 3,423,903 to Miller describes an apparatus for placing a valve bag on a spout by manipulation of the bag from a magazine by a series of suction cups mounted on an arm and rotated to a vertical position at which time the bag is passed from the pickup set of suction cups to another set of suction cups located on a tram arm. Controls then actuate a valve opening device after which the opening apparatus is retracted and the bag, held in place by the tram mounted suction cups and valve opening holding device moves the length of the tram to be deposited on a spout of the filling machine. This particular apparatus requires several different movements, each consuming a considerable amount of time, so that the total cycling time is still too high and does not permit optimum exploitation of the potential capacity of modern filling machines. Additionally, the suction cups must be absolutely clean, which is a near impossibility considering that you are filling the valve bags with granular material. Additionally the bags must be uniform and smooth with no creases, which is not generally possible. Additionally, Miller is not adapted for use on a filling machine having a plurality of spouts, i.e., stationary in-line filling machine or a rotary machine. Using Miller with the rotary machine would require a "stop-start" with a slight hesitation built in to position the spout in exact alignment to receive the bag from the bag placing machine. Miller is capable of functioning only with a single spout stationary filling unit.
U.S. Pat. No. 3,989,073 to Remmert describes another apparatus for mounting valve bags to filling spouts of filling machines. This machine, however, has a complicated control mechanism and elaborate scheme of operation not conducive to optimum operation.